Should You Cheat On Your Diet?

In discussions about dieting, a topic that often comes up is that of “cheating”; is it good or bad to cheat once in a while during a diet?

In order to answer this questions appropriately, it is necessary to look at both the quantitative and qualitative aspects of dieting, and the physiological and psychological responses they each elicit.

Dieting – what are we really talking about?

The dictionary definition of “diet” and “dieting” is “to eat and drink sparingly or according to prescribed rules” or “a controlled intake of foods, as for medical reasons or cosmetic weight loss”.

However, these definitions do not tell us anything about the two different aspects of dieting; the quantitative and qualitative parts, and their respective consequences. In everyday parlance, dieting usually implies both eating less calories (quantitative aspect) than usual and eating “specific” foods (qualitative aspect).

Nevertheless, when considering the consequences of “cheating” (more formally known as dieting consistency / inconsistency) and trying to answer the question whether it is a good or bad practice, it is important to distinguish these aspects of dieting. Let’s take a quick look at each:

Calorie restriction

Calorie restriction (also known as dietary restriction). When reducing calories our bodies respond by lowering basal metabolic rate, and there also is reduction is spontaneous physical activity. If the calorie restriction is severe enough, our bodies go into starvation mode, which will counteract any fat loss efforts 1,2.

Specific food restriction

A diet usually has an explicit (or implicit) list of foods that it recommends. Eating specific foods has a more psychological impact than calorie restriction per see, especially if you don’t like the foods that are part of your diet plan.

The different types of “cheating”

Now back to the issue of cheating. Looking at calorie restriction and specific food restriction separately, you see that that you can cheat in three different ways:

- eating more calories from the same “dieting foods” = quantitative cheating

Before we continue I want to make clear that this discussion on diet cheating (dieting consistency) should not be confused with yo-yo dieting (also called weight cycling; when one is repeatedly losing and regaining weight). Yo-yo dieting definitely has detrimental effects, especially psychologically 3,4.

Dieting consistency in this context is about maintaining the same diet regimen on weekends as on weekdays. For many people, diet and activity patterns differ substantially on weekends as compared to weekdays, with potential consequences on long term body fat weight that could promote the development or maintenance of excess fat storage and obesity if the pattern is repeated throughout the year.

Possible benefits and risk with cheating on a diet?

Allowing some diet flexibility on weekends, holidays, and vacations might reduce boredom, which is a known contributor to dieting lapses 5, and be more realistic from a long-term perspective. However, flexibility might also increase exposure to high-risk situations, a the chance for loss of control. This is especially true among people with addictive personalities 6.

What does the research say?

While it is well documented that holidays are associated with fat gain 7-9 it wasn’t until recently that studies started to investigate the influence of weekend eating patterns on short- and long-term body fat weight. The first study on weekend eating patterns was done on National Weight Control Registry subjects, who had successfully maintained a weight loss of at least 13.6 kg for 8 years 10. The purpose of the study was to examine whether maintaining the same diet regimen across the week and year promotes weight control or if dieting more strictly on weekdays and/or non-holidays is more conducive to long-term maintenance. Participants who reported greater dieting consistency were more likely to maintain their weight within 2.3 kg during the subsequent year, whereas participants with lower dieting consistency scores were more likely to regain weight during the subsequent year 10. A more recent study, where subjects consumed on average 236 calories more on weekend days, confirmed that weekend dietary indulgences contribute to weight gain or cessation of weight loss 11.

It has also been documented that as the duration of a diet increases, a shift in the balance between the effort and pleasure of weight maintenance may occur, which makes it easier to stick to the diet and thereby increases the likelihood of continued maintenance 12. This is supported by findings showing that repeated exposure trains flavor preference 13. In other words, a strong correlation exists between a person’s customary intake of a flavor and his preference for that flavor.

Bottom Line

Whether cheating on a diet (that is, a low diet consistency) will cause you any harm or good depends on your personal inclinations, and the reasons for the cheating.

From a biological perspective, I believe quantitative cheating, when you eat more calories from the same “dieting foods”, can be a good thing, since it can prevent lowering your resting metabolic rate and drops in spontaneous physical activity.

When it comes to the other types of cheating, the consequences are more of a psychological origin. If you have an addictive personality, do not even think about cheating. Remember, the best cure for any addiction is complete abstinence.

If you don’t have an addictive personality, but have a lot of fat to loose, it is ok for you to engage in quantitative or qualitative cheating on weekends, when you eat non-dieting “forbidden” foods, but still within your daily calorie allotment. But only do this if you feel that it helps you stay on track with your diet during the week days.

If you don’t have much fat to loose, and are just dieting to get in a little better shape, you can indulge in double whammy cheating, when you eat non-dieting “forbidden” foods AND exceed your daily calorie allotment. Just don’t go too much overboard; your body and mind will still take note of what you’re doing.

In any case, the reason for you to cheat on a diet should be that it helps you to stick to in the long run. Not because other people coerce you into it or are trying to make you believe that you “have to” cheat on your diet to get results. That’s nonsense you often hear from folks who don’t have the willpower and discipline themselves. It has actually been shown that friends have an even larger impact on a person’s risk of obesity than genes do 14. So don’t fall for the peer-pressure and never engage in risky behaviors because your friends do!

My advice to you is to be your own scientist and lab rat; try and see how you feel. If you lose control you know cheating on a diet is not for you, and you better put your foot down and stick to your guns. However, a slip doesn’t have to mean failure; turn the experience you gain from it into good data to guide your for future dietary decisions and long-term success!